1. Field of the Invention
The present application relates to a stereoscopic image display capable of selectively implementing a two-dimensional plane image (hereinafter referred to as “2D image”) and a three-dimensional stereoscopic image (hereinafter referred to as “3D image”).
2. Discussion of the Related Art
Recently, a stereoscopic image display capable of selectively implementing a 2D image and a 3D image has been developed and has been put on the market due to the development of various contents and circuit technology. Examples of a method for implementing the 3D image of the stereoscopic image display roughly include a stereoscopic technique and an auto-stereoscopic technique.
The stereoscopic technique, which uses a parallax image between left and right eyes of a user with a high stereoscopic effect, includes a glasses type method and a non-glasses type method, both of which have been put to practical use. In the non-glasses type method, an optical plate such as a parallax barrier for separating an optical axis of the parallax image between the left and right eyes is generally installed in front of or behind a display screen. In the glasses type method, left and right eye images, each of which has a different polarization direction, are displayed on a display panel, and a stereoscopic image is implemented using polarized glasses or liquid crystal (LC) shutter glasses.
An LC shutter glasses type stereoscopic image display alternately displays a left eye image and a right eye image on a display element every one frame and opens and closes a left eyeglass and a right eyeglass of LC shutter glasses in synchronization with a display timing, thereby implementing the 3D image. In the LC shutter glasses type stereoscopic image display, because the LC shutter glasses are turned on in a short period of time, a luminance of the 3D image is low. Further, a 3D crosstalk is extremely generated because of the synchronization between the display element and the LC shutter glasses and the ON/OFF conversion response characteristic.
In a polarized-glasses-type stereoscopic image display, a polarization separation device such as a patterned retarder is attached to a display panel. The patterned retarder separates the polarization of a left eye image and a right eye image displayed on the display panel. When a viewer views a stereoscopic image of the polarized glasses type stereoscopic image display using polarized glasses, the viewer sees the polarization of the left eye image through a left eye filter of the polarized glasses and sees the polarization of the right eye image through a right eye filter of the polarized glasses. Hence, the viewer may feel a stereoscopic feeling.
In the prior art polarized-glasses-type stereoscopic image display, a liquid crystal display panel may be used as the display panel. The prior art polarized glasses type stereoscopic image display provides a narrow vertical viewing angle due to the parallax between a pixel array of the liquid crystal display panel and the patterned retarder resulting from a thickness of an upper glass substrate of the liquid crystal display panel and a thickness of an upper polarizing plate. When the viewer views the stereoscopic image displayed on the polarized glasses type stereoscopic image display at a vertical viewing angle greater or less than an angle corresponding to the front of the liquid crystal display panel, the viewer may feel the 3D crosstalk in which the viewer sees a doubled image of the left and right eye images when viewing through one eye (the left eye or the right eye).
To solve the problem of the 3D crosstalk resulting from the narrow vertical viewing angle in the polarized-glasses-type stereoscopic image display, Japanese Laid Open Publication No. 2002-185983 proposed a method for forming black stripes on a patterned retarder (or 3D film) of a stereoscopic image display. Alternatively, there is a method for increasing a width of a black matrix formed on a liquid crystal display panel. However, the black stripes formed on the patterned retarder may reduce a luminance of 2D and 3D images and may interact with the black matrix to thereby cause moiré. The method for increasing the width of the black matrix reduces an aperture ratio and thus reduces the luminance of the 2D and 3D images.
To solve the problems of the stereoscopic image display disclosed in Japanese Laid Open Publication No. 2002-185983, Korean Patent Application No. 2009-0033534, filed on Apr. 17, 2009 and U.S. patent application Ser. No. 12/536,031, filed on Aug. 5, 2009, proposed a technique for dividing each of pixels of a display panel into two parts and using one of the two parts of each pixel as an active black stripe. The stereoscopic image display disclosed in the above-mentioned Korean and U.S. applications can prevent a reduction in the luminance of the 2D image by dividing each pixel into the two parts and displaying the 2D image on the two parts of each pixel in the 2D mode. Further, the stereoscopic image display can increase the vertical viewing angle of the 3D image by displaying the 3D image on one of the two parts of each pixel and displaying a black image on the other part in the 3D mode. However, in the stereoscopic image display using the active black stripe, the number of gate lines is doubled because each pixel is divided into the two parts. Hence, configuration of a gate driver is complicated.